Nabro volcano forms the central part of a large volcanic massif that straddles the Ethiopian/Eritrean border between the Danakil Depression and the Red Sea. Testament to a prehistory of major explosive eruptions, it has an 8-km-diameter summit crater and extensive rhyolitic ignimbrites cover its lower slopes. Nabro is on the Eritrean side of the border and directly faces the 6-km-diameter caldera of Mallahle volcano, forming a bizarre double caldera structure. Nabro’s caldera contains a young volcanic centre, topped by two additional collapse craters that were the focus of the 2011 eruption. The flanks of the volcano are strongly dissected by gullies, whereas the inner walls of the caldera form 400-m-high cliffs.
The 2011 eruption of Nabro had substantial impacts despite its remote location. It began shortly before 20:42 UTC on 12 June following intense seismicity. It produced ash clouds and a very considerable quantity of trachybasalt and basaltic trachyandesite lava. It is the first eruption of Nabro on record, highlighting the potential of caldera systems to erupt without warning. It is also the first seismicity of note recorded in this part of the rift. Several thousand people were displaced by the eruption and international aviation was disrupted by ash clouds. Satellite measurements rank the eruption among the largest sources of SO2 to the atmosphere since the 1991 Pinatubo eruption. Members of the CVG are working with numerous colleagues to understand the nature of the eruption and plumbing system of the volcano, and the timing and size of the major caldera-forming prehistoric eruptions.
- Wiart, Pierre; Clive Oppenheimer (2004). “Large magnitude silicic volcanism in north Afar: the Nabro Volcanic Range and Ma’alalta volcano”. Bulletin of Volcanology 67 (2): 99–115. doi:10.1007/s00445-004-0362-x